If you are interested in trying out Mac OS X Yosemite, but you aren't one of the 9 million registered developers already gaining access to the Beta today, you can sign-up on Apple's website today for your chance to be included in the Beta program

Apple offers Yosemite beta to first one million applicants today

If you are interested in trying out Mac OS X Yosemite, but you aren’t one of the 9 million registered developers already gaining access to the Beta today, you can sign-up on Apple’s website today for your chance to be included in the Beta program. The only catch is that you have to have an Apple ID and be one of the first 1 million individuals to sign up on their AppleSeed registration page.

I was able to sign-up a little over an hour ago and it was easy and painless. From Apple

OS X Yosemite will be available this fall. The OS X Beta Program lets you take part in shaping it by test-driving pre-release versions and letting us know what you think. Your comments will help us make OS X better for all Mac users. Sign up today, and the beta software will be available for you to install soon.